About halfway through Alan Ayckbourn's My Wonderful Day, there is a scene where a nine-year-old girl reads The Secret Garden – first aloud and then quietly to herself – while a man she barely knows snores in a chair opposite her. It lasts for about five minutes. The Stephen Joseph Theatre is in the round and the spectator's attention, as the minutes pass, shifts from the stage to the theatre itself, reflected back from raked seating to right and left, and down again to the child reading and the man sleeping.

It is impossible not to be aware that we are watching a play; yet, even as the time lapse forces us to recognise this, we are drawn deeper in to make-believes: the world we see and the world of the novel being read aloud to us. In that moment, a transformation happens as magical as the most magnificent pantomime transformation anyone could ever imagine, even though, on the stage, nothing changes. It's the transformation in each and every member of the audience, as the playwright dissolves the paraphernalia of our adult selves and uncovers that space inside each of us that is still the child we once were. It allows us, like Winnie, brilliantly played by Ayesha Antoine, to observe the "wonderful day" unfolding around her, with uncluttered eyes.

It's a typically Ayckbourn story – a farce of marital infidelity among media folk. All of the characters, except for Winnie and her cleaner mother, are trapped by the choices they don't have to make. In the presence of the child, they reveal the hopes and aspirations that their own actions prevent them from achieving. Even as we laugh at their ridiculousness, we feel compassion, perceiving that they, too, were children once, like the child Winnie is now; and recognising, as well, how ridiculous our adult selves might appear to the child we all once were.

If Ayckbourn's plays operated on the social rather than the personal scale, his techniques might be described as Brechtian – drawing attention, in an anti-illusionist way, to their own theatrical pretences. But where Ayckbourn aims to amuse by anatomising domestic decisions, Brecht aimed to instruct by deconstructing the social structures that compel people's choices.

In The Caucasian Chalk Circle (written in the United States in the early 40s), a fruit-growing co-operative lays claim to land that displaced goat breeders want to resettle. To make their point, the fruit growers present a play, narrated by a renowned visiting musician and based on two stories – one about a child, abandoned by its noble mother in time of uprising and raised by a peasant girl, the other about a paradoxical judge whose unjust methods bring just results.

The two stories merge in a Solomon-like judgment of the question: who should keep the child – the natural mother or she who raised him? Nancy Meckler's arresting and energetic production, with Alistair Beaton's new translation, reduces the setting to a launchpad for the story, which is delivered as part social satire, part heroic struggle of the peasant Grusha (an emotionally engaged Matti Houghton). I regretted the loss of the sense of a play within a play and the question it raises about the final decision, but, on the two nights I saw it, a young audience cheered the production to the rafters.

Trestle's The Glass Mountain also refracts contemporary realities through a folk tale. The four-strong company manipulates sets of stepladders to evoke a moving bus, an apple orchard, the eponymous mountain and a rolling Channel ferry as they convey stories of Polish migrants journeying to the UK: stunning images strengthen an occasionally wonky narrative.